MXPA97006383A - Coating composition based on a aglomerante containing oxhydryl groups, and its use inprocesses for the production of coatings - Google Patents

Abstract

The present invention relates to coating compositions comprising: (A) at least one binder containing hydroxyl groups, (B) at least one crosslinking agent, and (C) at least one mono and / or aromatic polycarboxylic acid. and / or at least one aromatic mono and / or polycarboxylic acid anhydride

Description

COATING COMPOSITION BASED ON A AGLOMERANT CONTAINING OXHYDRYL GROUPS, AND USE IN PROCESSES FOR THE PRODUCTION OF COATINGS The present invention relates to a coating composition comprising: (A) at least one binder containing hydroxyl groups, (B) at least one crosslinking agent.

The present invention is also related to processes for the production of protective and / or decorative coatings on a substrate surface and for the use of the coating compositions in the automotive finishing area.

DE-A-40 24 204 has already disclosed coating compositions containing, as a binder, a polyacrylate resin containing hydroxyl groups and which has been prepared in the presence of a polyester containing hydroxyl groups. However, especially when these coating compositions are applied at low temperatures, from about 8 to 12 BC, the resulting coatings need to improve the resistance to being removed by adhesive tape and the solvent resistance.

In the finishing area of large vehicles, for example, the finishing of bodies for goods vehicles, the resistance of the resulting coatings to be removed by adhesive tape is of particular importance. This is due to the fact that large vehicles are often provided with written characters, whose application requires that the adjacent area be covered with adhesive tape. If the resistance to being removed by adhesive tape is not adequate, the marks must be removed manually, by means of a hard sanding and polishing, which means a considerable financial outlay.

In addition, the coating compositions must also be cured as quickly as possible, in order to avoid excessive periods of standstill between the individual operations in the coating plant. Of course, these coating compositions must also possess good application properties and lead to coatings having good mechanical properties.

DE-A-31 33 769 discloses that the curing speed of amine-based coating compositions and compounds containing isocyanate groups can be increased by the addition of benzoic acid. DE-A-31 33 769 does not provide description of coating compositions based on binders containing hydroxyl groups and crosslinking agents containing isocyanate groups.

US-A-3, 897, 396 discloses that the curing speed of molding compositions based on polyurethaneurea can be increased by the addition of alkyl or alkoxybenzoic acid, without thereby decreasing the shelf life.

The molding compositions, known from US-A-3,897,396, contain polyamines as crosslinking agents and prepolymers as binders, which are based on reaction products of a polyether polyol, polyester polyol or hydrocarbopolyol with isocyanates.

Finally, DE-A-44 07 409 discloses coating compositions containing a polyacrylate resin containing hydroxyl groups and is based on hydroxy-n-butyl acrylate and a crosslinking agent. However, the preparation of the polyacrylate resin in the presence of a polyester resin is not described in this application.

The technical problem of the present invention is to provide coating compositions that exhibit rapid drying along with a long shelf life, that is, that can be processed in the ready-to-use state for a long period of time. In particular, the coating compositions must provide a resistance of the resulting coatings to be removed by adhesive tape, which is improved in comparison with that of conventional coating compositions. In addition, the coating compositions must at least meet the requirements conventionally imposed on a final layer or transparent layer. Thus, the coating compositions, for example, must exhibit good assimilation of the spray mist, good durability of the outer layer and good leveling. In addition, they should lead to coatings that have good solvent resistance and a high degree of surface hardness. In addition, the coating compositions must be cured at room temperature or at a slightly elevated temperature, so that they can be used in automotive finishing.

The technical problem of the present invention is surprisingly solved by providing coating compositions comprising: (A) at least one binder containing hydroxyl groups, (B) at least one crosslinking agent and (C) at least one aromatic mono and / or polycarboxylic acid and / or at least one anhydride of an aromatic mono and / or polycarboxylic acid.

The invention is further related to a process for the production of protective and / or decorative coatings on a substrate surface, using these coating compositions, and with the use of these coating compositions for finishing.

It is surprising, and it was not anticipated, that the coating compositions, according to the invention, even in curing at low temperatures, will cure quickly and at the same time maintain a long processability (shelf life). A particular advantage is the hiding resistance of the resulting coatings, which is improved compared to that of conventional coating compositions, and is of particular importance when the coating compositions are used in the finishing area of large vehicles.

An additional advantage is that the improvement of the resistance of the coatings to be removed by adhesive tape, surprisingly can be obtained without any deterioration of the leveling, duration of the outer layer and duration in the container. Finally, an additional advantage is that the resulting coatings have good solvent resistance and surface hardness.

The individual components of the coating compositions are now described in greater detail.

The coating compositions according to the invention contain as component (A) at least one binder containing hydroxyl groups.

Examples of the hydroxyl group containing binders that can be used as component (A) are polyester resins containing hydroxyl groups, alkyd resins containing hydroxyl groups, polyacrylate resins containing hydroxyl groups, polyurethane resins. containing hydroxyl groups, polyether resins containing hydroxyl groups, or mixtures of said resins containing hydroxyl groups. It is preferred to use as the component (A) polyester resins containing hydroxyl groups, alkyd resins containing hydroxyl groups, polyacrylate resins containing hydroxyl groups, or mixtures of said resins containing hydroxyl groups.

Polyester resins containing hydroxyl groups and alkyd resins containing hydroxyl groups are well known and can be obtained by reacting: pl) polycarboxylic acids or their esterifiable derivatives, together, if desired, with monocarboxylic acids, p2) polyols, together, if desired, with monooles, and p3) if desired, other modifying components.

Examples of polycarboxylic acids which can be used as component (pl) are cycloaliphatic, aliphatic and aromatic polycarboxylic acids. As the component (pl) it is preferred to use aliphatic and / or aromatic polycarboxylic acids.

Examples of polycarboxylic acids include italic acid, isophthalic acid, terephthalic acid, halophthalic acid, such as tetrachloro or tetrabromophthalic acid, adipic acid, glutaric acid, nonanodioic acid, sebacic acid, fumaric acid, maleic acid, trimellitic acid, pyromellitic acid. , tetrahydrophthalic acid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydroithalic acid, endomethylenetetrahydrophthalic acid, tricyclodecanedicarboxylic acid, endoethylenehexahydrophthalic acid, camphoric acid, cyclohexane tetracarboxylic acid, Cyclobutanetetracarboxylic acid, etc. The cycloaliphatic polycarboxylic acids can be used either in their cis form or in their trans form, or as a mixture of the two forms. Also suitable are the esterifiable derivatives of the polycarboxylic acids mentioned above, for example, their monoesters or multiple esters with aliphatic alcohols having 1 to 4 carbon atoms or hydroxyalcohols having 1 to 4 carbon atoms. In addition, it is also possible to employ the anhydrides of the acids mentioned above, when they exist.

If desired, monocarboxylic acids can be used together with the polycarboxylic acids, examples of which are benzoic acid, tert-butylbenzoic acid, lauric acid, isononanoic acid and naturally occurring fatty acids of oils. The monocarboxylic acid which is preferably used is isononanoic acid.

The polyol components (p2) suitable for the preparation of alkyd or polyester resins containing hydroxyl groups are polyhydric alcohols such as ethylene glycol, propanediols, butanediols, hexanediols, neopentyl glycol, diethylene glycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol, ethylbutylpropaniodol, ditrimethylolpropane, trimethylolethane. , trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, trishydroxyethyl isocyanurate, polyethylene glycol and polypropylene glycol. Examples of suitable monooles include butanol, octanol, lauryl alcohol and ethoxylated and / or proproxylated phenols.

Suitable components (p3) for the preparation of the alkyd or polyester resins containing hydroxyl groups are found in particular compounds containing a group that is reactive with respect to the functional groups of the alkyd or polyester resins. As the modifying component (p3) it is preferred to use diepoxide compounds and / or polyisocyanates and also - if desired - monoepoxide compounds and / or monoisocyanates. On page 4, lines 4 to 9, of DE-A-40 24 204 examples of suitable components (p3) are described. Also suitable as component (p3) are compounds which also contain, in addition to a group which is reactive with respect to alkenyl or polyester resin functional groups, a tertiary amine group, for example, monoisocyanates having at least one group tertiary amino or mercapto compounds having at least one tertiary amino group. For details, reference is made to DE-A-40 24 204, page 4, lines 10 to 49.

The polyester resins containing hydroxyl groups and the alkyd resins containing hydroxyl groups that are used as component (A) preferably have an OH number between 90 to 130, more preferably 90 to 110 mg KOH / g, an acid number of less than 12 mg KOH / g, preferably 1 to 8 mg KOH / g, an average molecular weight, by number, from 1300 to 3500, preferably from 1350 to 2000, and a polydispersity of 5 to 50, preferably from 5 to 10. Polydispersity is defined in this context as the ratio of the average molecular weight, by weight, to the average molecular weight, by number. The molecular weights of each case are determined by gel infiltration chromatography against a polystyrene standard.

Polyester resins containing hydroxyl groups and alkyd resins containing hydroxyl groups are prepared by known methods of esterification (cf. several standard works, for example: 1. Temple C. Patton, Al and Resin Technology, Interscience Publishers John iley & Sons, New York, London, 1962; Dr. Johannes Scheiber, Chemie und Technologie der künstlichen Harze [Chemistry and Technology of Synthetic Resins], Wissenschaftliche Verlagsgesellschaft mgH, Stuttgart, 1943; Hans Agner + Hans-Friedrich Sarx, Lackkunstharze [Synthetic Resins for Coatings], 4th edition, Karl Hanser Verlag, Munich, 1959; 4. Ullmanns Encyklop die der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], volume 14, pages 80 to 106 (1963)).

The reaction is conventionally carried out at temperatures between 180 and 280BC, in the presence, if desired, of an appropriate esterification catalyst, for example lithium octanoate, dibutyltin oxide, dibutyltin dilaurate, para-toluenesulfonic acid and the like.

The preparation of polyester resins containing hydroxyl groups and alkyd resins containing hydroxyl groups is conventionally carried out in the presence of small amounts of an appropriate solvent as entrainer. Examples of the entrainment agents used are aromatic hydrocarbons, particularly xylene and (cyclo) aliphatic hydrocarbons, for example cyclohexane.

Polyacrylate resins containing hydroxyl groups are also well known. They may contain, in addition to the hydroxyl groups, carboxylic groups and / or amide groups and / or epoxy groups, preferably carboxylic groups. The polyacrylate resins containing hydroxyl groups used as component (A) preferably have an OH number within the range of 20 to 360 mg KOH / g, more preferably between 50 to 150 mg KOH / g, and most preferably preferably between 70 to 105 mg of KOH / g and an acid number within the range of 0 to 140 mg of KOH / g, preferably between 0 to 50 mg of KOH / g, more preferably between 0 to 12 mg of KOH / g most preferably from 0 to 4 mg of KOH / g. Preferably, polyacrylate resins containing hydroxyl groups having an average molecular weight, by number, of at most 10,000 are used, whereby polyacrylate resins having an average molecular weight, by number, of 1,000 to 5,000, preferably from 2000 to 4000, are particularly preferred. The average molecular weight, by number, is determined by gel infiltration chromatography, using polystyrene as the norm.

Polyacrylate resins containing hydroxyl groups can be prepared according to usual processes, such as, for example, solution polymerization in the presence of an initiator and, optionally, in the presence of a polymerization regulator. The polymerization is carried out at temperatures within the range of 100 to 180 aC. Initiators containing peroxide groups, initiators containing azo groups and thermolabile compounds, such as, for example, compounds based on highly substituted ethane derivatives, are suitable as initiators.

For the preparation of the polyacrylate resins containing hydroxyl groups, all the monomers that are usually used for this purpose can be used.

The monomers containing hydroxyl groups are, for example, hydroxyalkyl esters of unsaturated α, β-carboxylic acids, with compounds containing primary or secondary hydroxyl groups. If a high reactivity of the acrylic copolymer is desired, hydroxyalkyl esters having exclusively primary hydroxyl groups can be employed. If it is intended that the polyacrylate be less reactive, hydroxyalkyl esters having only secondary hydroxyl groups can be used. Of course, mixtures of hydroxyalkyl esters having primary hydroxyl groups and hydroxyalkyl esters having secondary hydroxyl groups can be employed.

Examples of hydroxyalkyl esters of unsaturated carboxylic acids a and β, with compounds having primary hydroxyl groups are hydroxyethyl acrylate, 3-hydroxy-n-propyl acrylate, 4-hydroxy-n-butyl acrylate, acrylate. of hydroxyamyl, hydroethyl acrylate and hydroxyoctyl acrylate, as well as the corresponding methacrylates. As examples of suitable hydroxyalkyl esters having secondary hydroxyl groups may be mentioned 2-hydroxybutyl acrylate, 3-hydroxy-n-butyl acrylate, as well as also the corresponding methacrylates. It is not necessary to mention that the corresponding esters of other unsaturated α and β carboxylic acids can also be used, for example, esters of crotonic acid or isocrotonic acid.

Preferably, the monomer containing hydroxyl groups may, at least partially, be a reaction product of 1 mole of hydroxyethyl acrylate and / or hydroxyethyl methacrylate and, on average, 2 moles of ε-caprolactone. As the monomer containing hydroxyl groups, a reaction product of acrylic acid and / or methacrylic acid with an equivalent amount of a glycidyl ester of a carboxylic acid having a carbon atom to tertiary can also be used, at least partially. . The glycidyl esters of highly branched monocarboxylic acids (for example, branched carboxylic acids having 11 to 13 carbon atoms (Versatic acid)) can be obtained commercially under the tradename "Cardura". The reaction of said acrylic acid or methacrylic acid with said glycidyl ester of a carboxylic acid having a carbon atom to tertiary can be carried out before, during or after the polymerization reaction.

Hydroxypentyl (meth) acrylates, hydroxyhexyl (meth) acrylates and hydroxyoctyl (meth) acrylates can also be used as monomers containing hydroxyl groups.

In addition, the aliphatic and cycloaliphatic esters of carboxylic acids with unsaturated ethylene, such as, for example, aliphatic or cycloaliphatic esters of (meth) acrylic acid, crotonic acid, isocrotonic acid and maleic acid are suitable monomers for the preparation of the polyacrylate resins containing hydroxyl groups. Examples of said monomers are methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylate t-butyl, isopropyl (meth) acrylate, pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, (meth) isoamyl acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, furfuryl (meth) acrylate, octyl (meth) acrylate, 3,5,5-trimethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, stearyl (meth) acrylate and ethyltriglycol (meth) acrylate.

In addition, vinylaromatic compounds are also suitable comonomers. Preferably, the vinylaromatic compound contains from 8 to 9 carbon atoms per molecule. Styrene, vinyltoluenes, α-methylstyrene, chlorostyrenes, o-, m- and p-methylstyrene, 2,5-dimethylstyrene, p-methoxystyrene, pt-butylstyrene, p-dimethylaminostyrene, p-acetamidostyrene and m-vinylphenol are examples of comonomers appropriate. Preferably vinyltoluenes are used as well as styrene in particular.

Additional suitable comonomers include alkoxyethyl acrylates, aryloxyethyl acrylates, as well as the corresponding methacrylates, such as, for example, butoxyethyl (meth) acrylate and phenoxyethyl (meth) acrylate, as well as (meth) acrylic acid, (met ) acrylamide, (meth) acrylonitrile and alkyl esters of other carboxylic acids with unsaturated ethylene, for example, alkyl esters of crotonic acid and isocrotonic acid, as well as polymerizable vinyl esters and vinyl esters, such as vinyl esters of monocarboxylic acids, preferably vinyl esters of branched monocarboxylic acids having from 5 to 15 carbon atoms per molecule. The branched monocarboxylic acids can be obtained by reacting formic acid or carbon monoxide and water with olefins, in the presence of a liquid catalyst, strongly acidic; olefins can be products of the cracking of paraffinic hydrocarbons, such as fractions of mineral oil, and can contain both straight and branched chain cycloaliphatic and / or acyclic olefins. In the reaction of said olefins with formic acid or with carbon monoxide and water, a mixture of carboxylic acids is formed in which the carboxyl groups are predominantly located in a quaternary carbon atom. Examples of other initiator olefinic materials include propylene trimer, propylene triprimer and diisobutylene. Vinyl esters can also be produced from the acids in a manner known per se, for example, by reacting the acids with acetylene. The vinyl esters of saturated aliphatic monocarboxylic acids having 9-11 carbon atoms and branched at the carbon atom are readily available. In addition, particular preference is given to the p-tertiary butylbenzoic acid vinyl ester. Examples of other vinyl esters are vinyl acetate and vinyl propionate.

Preferred polyacrylate resins are polyacrylate resins containing one or more monomers selected from the group consisting of 4-hydroxy-n-butyl acrylate, 4-hydroxy-n-butyl methacrylate, 3-hydroxy-n-butyl acrylate. and 3-hydroxy-n-butyl methacrylate, together, if desired, with hydroxyethyl methacrylate.

The preparation of the polyacrylate resins which are used according to the invention can be carried out by polymerization methods which are generally well known. Polymerization methods for the preparation of polyacrylate resins are generally known and have been described in numerous references (cf., for example: Houben-Weyl, Methoden der oganischen Chemie [Methods in Organic Chemistry] 4 * edition, volume 14/1, pages 24 to 255 (1961)).

The polyacrylate resins containing hydroxyl groups which are used according to the invention are preferably prepared using the solution polymerization method. In this method, it is conventional to take an organic solvent or solvent mixture and heat the mixture until it boils. The mixture of monomer to be polymerized and one or more polymerization initiators are then added continuously to the organic solvent or to the solvent mixture. Polymerization occurs at temperatures between 100 and 160 ° C, preferably between 130 and 150 ° C.

The polymerization is preferably carried out in an organic solvent with a high boiling point, which is inert with respect to the monomers used. Examples of suitable solvents are aromatics with high substitution, for example, Naphtha solvent, heavy benzene, various grades of Solvesso, various grades of Shellsol and Deasol, and aliphatic and cycloaliphatic hydrocarbons with a relatively high boiling point, example, various white alcohols, turpentine mineral oil, tetralin and decalin and various esters, for example ethylene glycol acetate, butyl glycol acetate, ethyldiglycol acetate and the like.

The polymerization initiators that are preferably used are initiators that form free radicals. The nature and amount of initiator are usually selected such that, at the polymerization temperature, the supply of free radicals is substantially constant during the feed phase.

Among the cited examples of initiators that may be employed are di-tert-butyl peroxide, tere-butyl hydroperoxide, tere-butyl peroxybenzoate, tere-butyl peroxypivalate, tertiary butyl-3,5,5-trimethyleneoxanoate , tertiary butyl peroxy-2-ethylhexanoate, dicumyl peroxide, cumyl hydroperoxide, tert-amyl peroxybenzoate, tert-amyl peroxy-2-ethylhexanoate, diacyl peroxides, for example, diacetyl peroxide, peroxycetals, , 2-di (tert-amylperoxy) propane, ethyl 3,3-di (t-amylperoxy) butyrate and highly substituted, thermally labile ethane derivatives, based, for example, on ethane derivatives with silyl substitution and in benzopinacol. In addition, it is also possible to use aliphatic azo compounds, for example azoisovaleronitrile and azobiscyclohexanonitrile.

In most cases, the amount of initiator is 0.1 to 8%, by weight, based on the amount of monomer to be processed, although it may be even higher, if desired. The initiator, dissolved in a part of the solvent used for the polymerization, is introduced gradually during the polymerization reaction. The addition of initiator preferably takes about 0.5 to 2 hours longer than the addition of monomer, in order to also obtain a good action during the post-polymerization phase. In another preferred variation of the preparation, the addition of initiator is started approximately 15 minutes before the addition of the monomers, in order to ensure a good supply of free radicals at the beginning of the polymerization. If initiators are used that only have a low decomposition rate under the prevailing reaction conditions, then it is also possible to include the initiator in the initial charge.

The polymerization conditions (reaction temperature, addition time of the monomer mixture, nature and amount of the organic solvents and polymerization initiators, possible use of molecular weight regulators, for example mercaptans, thioglycol esters and hydrogen compounds containing chlorine) are selected such that the polyacrylate resins used according to the invention have the desired molecular weight.

The acid number of the polyacrylate resins used according to the invention can be adjusted by the right-handed person in the guild, by the use of appropriate amounts of monomers containing carboxyl groups (for example acrylic or methacrylic acid). Similar comments apply to adjusting the hydroxyl number. It can be controlled by the amount of monomers containing hydroxyl groups that can be used.

Preferred polyacrylate resins containing hydroxyl groups can be obtained by polymerizing (a) from 5 to 50%, by weight, preferably from 10 to 35%, by weight, of one or more monomers selected from the group consisting of 4-hydroxy-n-butyl acrylate, 4-hydroxymethyl methacrylate -butyl, 3-hydroxy-n-butyl acrylate, 3-hydroxy-n-butyl methacrylate and / or hydroxyethyl methacrylate. (b) from 0 to 50%, by weight, preferably from 0 to 30%, by weight, of a monomer copolymerizable with unsaturated ethylene, which is different from (a) and contains hydroxyl groups, or a mixture of said monomers , (c) from 5 to 95%, by weight, preferably from 15 to 55%, by weight, of an aliphatic and / or cycloaliphatic ester of methacrylic and / or acrylic acid which is different from (a) and (b), or a mixture of said monomers, (d) from 0 to 30%, by weight, preferably from 5 to 15%, by weight, of a copolymerizable vinyl ester which is different from (a), (b) and (c), or a mixture of said monomers, (e) from 0 to 85%, by weight, preferably from 15 to 60%, by weight, of an aromatic vinyl hydrocarbon that is different from (a), (b), (c) Y (d) / or a mixture of said monomers, and (f) from 0 to 10%, by weight, preferably from 0 to 8%, by weight, of an additional monomer with unsaturated ethylene, which is different from (a), (b), (c), (d) and (e), or a mixture of said monomers, the sum of the proportions, by weight, of the monomers (a) to (f) in each case will be 100%, by weight.

In addition, polyacrylate resins containing hydroxyl groups described in German Patent Application No. DE-A 38 23 005, page 2, line 52, page 6, line 19, as well as in German Patent Application No. DE-A 35 34 874, from page 4, line 43, to page 6, line 52.

Also suitable are polyacrylate resins containing carboxyl groups, described in German Patent Application No. DE-A 39 18 669, page 2, line 59, page 7, line 2, as well as in German Patent Application No. DE-A 41 33 420, from page 2, line 61, to page 6, line 60.

In addition, polyacrylate resins containing hydroxyl groups are suitable, as described in the unpublished German Patent Application No. P 44 07 415.8, which can be obtained by polymerizing: (i) 0 to 80%, by weight, preferably 0 to 30%, by weight, of a cycloaliphatic ester of methacrylic acid and / or acrylic acid, or a mixture of these monomers; (m 2) 10 to 50%, by weight, preferably 15 to 40%, by weight, of an alkyl ester containing hydroxyl groups, methacrylic acid and / or acrylic acid, or a mixture of said monomers; (m3) 0 to 25%, by weight, preferably 0 to 15%, by weight, of a monomer, containing hydroxyl groups, with unsaturated ethylene, other than (mj) and (m2), or a mixture of these monomers; (m4) 5 to 80%, by weight, preferably 5 to 30%, by weight, of an aliphatic ester of methacrylic acid and / or acrylic acid, other than (mj), (m2) and (m3), or a mixture of these monomers; Y (m5) 0 to 40%, by weight, preferably 10 to 30%, by weight, of a vinylaromatic hydrocarbon other than (m :), (m2), (m3), and (m4), or a mixture of these monomers; Y (m6) 0 to 40%, by weight, preferably 0 to 30%, by weight, of an additional monomer with unsaturated ethylene, other than (mj), (m2), (m3), (m ") and ( m5) or a mixture of these monomers; to a polyacrylate resin having an average molecular weight, by number, Mn, from 1,000 to 5,000, a ratio of the average molecular weight, by weight, Mw, to the average molecular weight, by number, Mn, of less than 5.0, preferably from 1.8 to 4.0, and an OH number from 60 to 180 mg of KOH / g, preferably 100 to 150 mg of KOH / g, whereby the sum of the weight portions of the components (mj) to (m6) is always 100%, by weight, and therefore they use only monomers or mixtures of monomers as component (m2) which, when the respective polymer is polymerized alone, results in a polyacrylate and / or polymethacrylate resin having a glass transition temperature of -10 ° C to + 6 ° C, or + 60 ° C. at 80 aC.

The use of the polyacrylate resins indicated above results in coating compositions which, when used as a clearcoat varnish, yield coatings exhibiting improved adhesion relative to conventional coatings.

As the component (m2), preferably 3-hydroxypropyl methacrylate and / or 2-hydroxypropyl methacrylate and / or 3-hydroxypropyl acrylate and / or 2-hydroxypropylacrylate are used. Examples of suitable monomers such as (mi) and (m3) to (m6) are the monomers described above.

In addition, the polyacrylate resins described in German Patent Application No. P 44 07 409.3, which can be obtained by polymerizing, are suitable.

(Pi) 10 to 51%, by weight, of a mixture of (pn) one or more monomers selected from the group of 4-hydroxy-n-butyl acrylate and / or 4-hydroxy-n-butyl methacrylate and / or 3-hydroxy-n-butyl acrylate and / or 3-methacrylate methacrylate. -hydroxy-n-butyl, and (p12) one or more monomers selected from the group of 3-hydroxy-n-propyl acrylate and / or 3-hydroxy-n-propyl methacrylate and / or 2-hydroxy-n-propyl acrylate and / or 2-methacrylate methacrylate -hydroxy-n-propyl; (p2) 0 to 22%, by weight, of an ester, containing hydroxyl groups, of acrylic acid or methacrylic acid other than (px), and having at least 5 carbon atoms in the alcohol residue, or a mixture of said monomers; (p3) 28 to 85%, by weight, of an aliphatic or cycloaliphatic ester of acrylic acid or methacrylic acid other than (p?) and (p2), and having at least 4 carbon atoms in the alcohol residue, or a mixture of said monomers; (p4) 0 to 25%, by weight, of a vinylaromatic hydrocarbon, other than (px), (p2) and (p3), or a mixture of said monomers; (p5) 0 to 5%, by weight, of a carboxylic acid with unsaturated ethylene or a mixture of carboxylic acids with unsaturated ethylene; Y (p6) 0 to 20%, by weight, of an unsaturated ethylene monomer, other than (px), (p2), (p3), (p ") and (p5), or a mixture of said monomers; to a polyacrylate resin having a hydroxyl number of 60 to 200 mg KOH / g, an acid number of 0 to 35 mg KOH / g and an average molecular weight, by number, of 1,000 to 5,000, where the sum of the portions of the weight of the components (p :) to (p6) is always 100%, by weight.

The use of the polyacrylate resins indicated above results in coating compositions which, when used as clear coat varnish, provide coatings that exhibit improved adhesion compared to conventional coatings.

The coating compositions, according to the present invention, more preferably contain, as component (A), a binder comprising (Al) from 20 to 60%, by weight, preferably from 30 to 50%, by weight, of at least one alkyd or polyester resin containing hydroxyl groups, and (Al) from 40 to 80%, by weight, preferably from 50 to 70%, by weight, of at least one polyacrylate resin that has been prepared, at least partially, - in the presence of the component (Al).

The binder composed of (Al) and (A2) preferably has an hydroxyl number of from 80 to 150, particularly preferably from 85 to 105 mg of KOH / g, and an acid number from 0.1 to 12, preferably from 4 to 8 mg. from KOH / g.

The alkyd or polyester resins containing hydroxyl groups described above can be used as component (Al) and the polyacrylate resins containing hydroxyl groups described above can be used as component (A2). Also suitable as component (A2) are polyacrylate resins with an OH number within the range of 0 to 20 mg KOH / g.

It is essential that the polyacrylate resin (A2) be prepared, at least partially, in the presence of the alkyd or polyester resin containing hydroxyl groups (Al).

The initiators used are preferably those containing tere-butyl groups, for example di-tert-butyl peroxide, tere-butyl hydroperoxide, 2,2-di-tert-butylperoxybutane and 1,3-bis (tert-butylperoxypropyl) benzene, since they promote the grafting of the polyacrylate resin in the alkyd or polyester resin.

The possible residual amount of the component (A2) is subsequently added to the binder solution or the coating composition. In this context, it is possible that this added resin has the same monomer composition as the addition polymer resin created in the presence of the polymeric condensation resin. However, it is also possible to add an addition polymer resin having a different monomer composition. In addition, it is possible to add a mixture of different polymeric addition resins.

Polyurethane resins containing hydroxyl groups are well known. Polyurethane resins containing hydroxyl groups can be obtained by reacting: i) alkyd or polyester resins containing hydroxyl groups and / or polyether resins containing hydroxyl groups; ii) optionally at least one compound other than (i), which contains at least one hydroxyl group and / or at least one primary or secondary amino group, and iii) at least one polyisocyanate.

Polyether resins containing hydroxyl groups are also well known. Examples of polyester resins containing hydroxyl groups are poly (oxyethylene) polyols, poly (oxypropylene) polyols and poly (oxyethylene) (oxypropylene) polyols.

The coating compositions, according to the invention, contain as component (B) at least one crosslinking agent. Examples of crosslinking agents that can be used as component (B) are polyisocyanates, aminoplast resins and polyepoxides or mixtures of polyisocyanates, aminoplast resins and polyepoxides, or mixtures of polyisocyanates and aminoplast resins, or mixtures of polyisocyanates and polyepoxides, or mixtures of aminoplast resins and polyepoxides. It is preferred to use polyisocyanates and mixtures of polyisocyanates and aminoplast resins as the crosslinking agent (B). A very particular preference is given to employing at least one polyisocyanate as a crosslinking agent (B).

As the crosslinking agent (B), any organic polyisocyanate containing free isocyanate groups which bind to aliphatic, cycloaliphatic, araliphatic and / or aromatic structures is suitable. The polyisocyanates which are preferably used are those containing 2 to 5 isocyanate groups per molecule. It is possible, if desired, to add to the polyisocyanates small amounts of organic solvent, preferably 1 to 25%, by weight, based on pure polyisocyanate, in order to improve the ease of incorporation of the polyisocyanate. Examples of solvents which are suitable as additives for the polyisocyanates are ethoxyethyl propionate, butyl acetate and the like.

Examples of suitable polyisocyanates are described in, for example, "Methoden der organischen Chemie" [Methods in Organic Chemistry], Houben-Weyl, volume 14/2, 4th edition, Georg Thieme Verlag, Stuttgart 1963, pages 61 to 70 and by. Siefken, Liebigs Ann. Chem. 562, 75 to 136.

Suitable examples include 1,2-ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4- or 2,4,4-trimethyl-1,3-diisocyanate. hexamethylene, 1,2-dodecane diisocyanate, diisocyanate dipropyl ether, 1,3-cyclobutane diisocyanate, 1,3- and 1,4-cyclohexane diisocyanate, 2,4- and 2,6-diisocyanate-1 -methylcyclohexane, isocyanate of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl ("isophorone diisocyanate"), 2,5- and 3,5-bis (isocyanatomethyl) -8-methyl-1,4-methaneddecahydronaphthalene, 1, 5-, 2,5-, 1,6- and 2,6-bis (isocyanatomethyl) -4,7-methanohexahydroindane, 1,5-, 2,5-, 1,6- and 2,6-bis (isocyanate) ) -4, 7-methanohexahydroindane, 2,4'- and 4,4-dicyclohexyl-diisocyanate, 2,4- and 2,6-hexadidrotholylene diisocyanate, perhydro-2,4'- and -4,4-diisocyanate '-diphenylmethane, * -diisocyanate-l, 4-diethylbenzene, 1,3- and 1,4-phenylene diisocyanate, 4,4'-diisocyanatobiphenyl, 4,4'-diisocyanato-3,3'-dichlorobiphenyl, 4,4'-diisocyanate-3, 3 • -dimethylbiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 4,4'-diisocyanato-3,3 '-diphenylbiphenyl, 2,4'- and 4,4'-diisocyanato-diphenylmethane, 1,5-naphthylene diisocyanate, toluene diisocyanates, such as 2,4-diisocyanate 2,6-tolylene, N, N * - (4,4'-dimethyl-3,3'-diisocyanato-biphenyl) uretdione, m-xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, and also triisocyanates, such as 2,4,4'-triisocyanatodiphenylether and 4,4 ', 4 • • -tri-isocyanatotriphenylmethane. The polyisocyanates preferably used, in combination, if desired, with the polyisocyanates mentioned above, are those containing isocyanurate groups and / or biuret groups and / or allophanate groups and / or urethane groups and / or urea groups. Urethane groups containing polyisocyanates are obtained, for example, by reacting some of the isocyanate groups with polyols, such as polyalkylene glycols, alkyd resins, neopentyl glycol, hexanotriol, tri-ethylolpropane and glycerol.

It is preferable to use aliphatic and cycloaliphatic polyisocyanates, especially hexamethylene diisocyanate, dimerized and trimerized hexamethylene diisocyanate, isophorone diisocyanate, 2,4'-dicyclohexylmethane diisocyanate or 4,4'-dicyclohexylmethane diisocyanate or mixtures of these polyisocyanates. Particular preference is given to using mixtures of polyisocyanates containing uretdione groups and / or isocyanurates and / or allophanate groups, and which are based on hexamethylene diisocyanate, or which are formed by the catalytic oligomerization of hexamethylene diisocyanate, using catalysts appropriate. Otherwise, any desired mixture of the aforementioned polyisocyanates can be used as component (B).

However, coated polyisocyanates can also be used, for example, the polyisocyanates described above, which are reacted with the customary coating agents, for example, with phenols, alcohols, acetoacetic acid esters, ketoximes and β-caprolactam. These compositions are stable at room temperature and are generally cured at temperatures only above 100 ° C. In particular cases, for example, when used with acetoacetic acid esters to cover, a crosslinking may already occur at less than 100BC.

The amount of the crosslinking agent employed is selected such that the ratio of the isocyanate groups of the crosslinking agent (B) to the hydroxyl groups of the binder component (A) is within the range of 1: 3 to 3: 1. .

If the binder (A) contains carboxy groups as the functional groups, polyepoxide compounds having at least 2 epoxy groups per molecule can be used as crosslinking agents. Aliphatic and / or alicyclic polyepoxides are particularly preferred, since they result in low yellowing. The polyepoxide is usually employed in an amount such that the ratio of free carboxyl groups in the binder (A) to the epoxy groups in the polyepoxide is within the range of 1: 3 to 3: 1.

Among the examples of polyepoxide suitable as crosslinking agents are cycloaliphatic bisepoxides; epoxidized polybutadienes that originate from a reaction of polybutadiene oils, which can be obtained commercially, with peracids or mixtures of organic acids and H202, respectively, epoxidation products of fats, oils, fatty acid derivatives and modified oils found in the nature, novolaks containing epoxy groups, glycidyl ethers of polyhydric alcohols, for example, diglycidyl ether of ethylene glycol, polyglycidyl ether of glycerol, polyglycidyl ether of sorbitor, polyglycidyl ether of trimethylolpropane, and polyglycidyl ether of pentaerythritol, as well as resins of polyacrylate having oxirane groups in the side chain. In addition, as crosslinking agents, reaction products of polyepoxides containing hydroxyl groups with di or polyisocyanates can be used, for example, the compounds obtained by a reaction of OH-functional epoxides (for example, polyglycidyl ethers of sorbitol) with diisocyanate of isophorone.

Polar polyepoxides are also suitable as crosslinking agents, for example, compounds based on a reaction product of melamine resins with acrylamide, with the subsequent epoxidation of the double acrylic bond. An example of this class of substances are the products "Santolink LSE 114" and "Santolink LSE 120", from Monsanto Company, which can be obtained commercially. In these products, the epoxy resin skeleton is a binuclear melamine, where the average molecular weight, by number, is about 1,200 to 2,000 and the equivalent weight of epoxide is about 300 to 350.

The coating compositions, according to the invention, usually contain from 15 to 50%, preferably 20 to 40%, by weight, of component (A), and from 6 to 50%, preferably from 6 to 20%, by weight , of the crosslinking agent (B), based in each case on the total weight of the coating composition.

The coating compositions according to the invention contain as component (C) at least one aromatic mono and / or polycarboxylic acid and / or at least one anhydride of an aromatic mono and / or polycarboxylic acid. The component (C) is usually added to the binder component (A). The component (C) is preferably added to the binder component (A) after its preparation. The component (C) can also be added to the finished coating composition, for example, after the addition of pigments, fillers, auxiliaries and crosslinking agents. However, preferably, the component (C) is added to the binder component (A) and dispersed to provide a maximum degree of homogeneity.

Examples of aromatic mono and polycarboxylic acids and anhydrides of aromatic mono and polycarboxylic acids suitable as component (C) are phthalic anhydride, phthalic anhydride with alkyl and / or alkoxy substitution, phthalic anhydride half-esters, phthalic anhydride half-esters with substitution of alkyl and / or alkoxy, benzoic acid, benzoic acid with alkyl and / or alkoxy substitution, and mixtures of said aromatic mono and polycarboxylic acids and anhydrides of aromatic mono and polycarboxylic acids. It is particularly preferred to add benzoic acid as component (C).

The amount of component (C) is preferably 0.1 to 2%, by weight, more preferably 0.1 to 1%, by weight, most preferably 0.4 to 0.9%, by weight, based on the weight of the binder component ( A), which contains hydroxyl groups, calculated as solid resin, for example, without the solvent fraction.

The acid is preferably added at a temperature of 20 to 120aC, particularly preferably at a temperature of 40 to 100aC.

The anhydride is preferably added at a temperature of 100 to 180 aC, particularly preferably at a temperature of 130 to 170 aC.

The coating compositions, according to the invention, also contain one or more organic solvents.

These solvents are usually used in amounts of 20 to 70%, by weight, preferably 30 to 60%, by weight, based in each case on the total weight of the coating composition.

Examples of suitable solvents are aromatic compounds with a relatively high substitution, for example solvent naphtha, heavy benzene, various grades of Solvesso, various grades of Shellsol and Deasol, and cycloaliphatic and aliphatic hydrocarbons as a relatively high boiling point, example, various white alcohols, turpentine mineral oil, tetralin and decalin, and various esters, for example ethylglycol acetate, butyl glycol acetate, ethyldiglycol acetate and the like.

The coating compositions, according to the invention, may additionally contain additives and conventional auxiliaries, in conventional amounts, preferably from 0.01 to 10%, by weight, based on the total weight of the coating composition. Examples of suitable additives and auxiliaries are leveling agents, such as silicone oils, plasticizers, such as phosphoric esters and italic esters, additives for viscosity control, opacifying agents, ultraviolet light absorbers, light stabilizers, agents for give texture and, you want, fillings.

In addition, the coating compositions, according to the present invention, can have reactive diluents, such as polyaldimines, for example, the reaction product of isobutyraldehyde and isophorone diamine and / or secondary amines.

The coating compositions according to the invention may also contain conventional pigments in conventional amounts, preferably from 0 to 40%, by weight, based on the total weight of the coating composition. Examples of suitable pigments include organic, inorganic, metallic and other effects pigments.

The coating compositions are prepared in a known manner, mixing and - if desired - dispersing the individual components.

These coating compositions can be applied to a substrate, by flow coating, spraying, immersion, roller, knife or brush, in the form of a film, and the film subsequently cured to provide a firmly adhering coating.

The curing of these coating compositions is carried out conventionally at room temperature or at a slightly elevated temperature, preferably at a slightly elevated temperature, advantageously at temperatures below 120 ° C. and preferably at temperatures between 80 ° C. and 60 ° C. However, the coating compositions can also be cured under bake conditions, for example, at temperatures of at least 120 BC.

Particularly suitable substrates are metals, and also wood, plastic, glass and the like.

Due to the short curing times and the low curing temperatures, the coating compositions according to the invention are preferably used for automotive finishes, and for the finishing of large-sized vehicle bodies and freight vehicles. However, depending on the crosslinking agent employed, they can also be used for the finishing, in the production line, of motorized vehicles. In addition, they are particularly suitable as a solid color final coat. However, of course they can also be used as a primer, basecoat and clearcoat, particularly on a metallic basecoat or a solid-colored basecoat.

The present invention is also related to a process for the production of a protective and / or decorative coating on a substrate surface, and said process is characterized in that a coating composition according to the invention is applied. - The invention is now illustrated in more detail, with reference to examples of embodiments. All parts and percentages of these examples are by weight, unless expressly indicated otherwise.

Example I A pigmented coating composition was prepared, with 169.3 parts of a black pigment dispersion (1.6% black carbon pigment dispersed in 53.8% acrylic copolymer of 24% methyl methacrylate, 20% styrene, 27.5% methacrylate hydroxyethyl, 17.6% isodecyl methacrylate and 10.9% n-butyl acrylate (average molecular weight, by number, less than 2500, average molecular weight, by weight, less than 6500) with 2.1% additive adjuvants dispersion in 42.5 % of common solvents in the guild), 82.8 parts of a polyisocyanate mixture (31% of isocyanurate of hexamethylene diisocyanate and 10.4% of isocyanurate diisocyanate of isoiorone in 58.6% of common solvents in the guild), 72.6 parts of a reducing mixture ( 4.1% of ultraviolet light absorbent, dibutyltin dilaurate and additives for slip and wear in 95.9% of solvents known in the trade) and 0.8 parts of benzoic acid. This coating composition exhibited a very fast drying time.

Example II A non-pigment (transparent) coating composition containing an acrylic copolymer of 14.2% styrene, 18.7% n-butyl methacrylate, 33.1% methyl methacrylate, 33.8% hydroxypropyl methacrylate and 0.3% methacrylic acid (weight average molecular weight, by number, of less than 10,000), trimerized hexamethylene diisocyanate and 0.25% benzoic acid, had a better shelf life.

III.1. Preparation of a polyester resin Al; 796 parts of triraethylolpropane, 540 parts of isononanoic acid, 821 parts of italic anhydride and 83 parts of xylene were placed in a 4 liter condensation polymerization vessel equipped with stirrer, steam heated column and water separator, and They warmed up slowly. The condensation was carried out at a temperature of a maximum of 190 ° C, up to an acid number of 5 mg KOH / g and a viscosity of 8.0 dPas (60% in xylene). The batch was then enriched, diluted to 130 ° C with 910 parts of Shellsol A, and further enriched at room temperature.

The resulting polyester has a solids content of 66.5%, an acid number of 5 mg KOH / g, a number (theoretical) OH of 97.2 mg KOH / g and a viscosity of 70 dPas (original). The average molecular weight, by number, Mn, is 1493, the average molecular weight, by weight, Mw, is 13.243, and the polydispersity Mw / Mri is 8.87 (each determined by the gel chromatography on a polystyrene nopria). ).

III.2. Preparation of a polyester A2 resin: 796 parts of trimethylolpropane, 540 parts of isononanoic acid, 821 parts of italic anhydride and 83 parts of xylene were placed in a 4 liter condensation polymerization vessel equipped with stirrer, steam heated column and water separator, and They warmed up slowly. The condensation was carried out at a temperature of a maximum of 190BC, up to an acid number of 10 mg KOH / g and a viscosity of 7.2 dPas (60% in xylene). The batch was then enirió, diluted to 130BC with 910 parts of Shellsol A, and further enriched at room temperature.

The resulting polyester has a solids content of 65.4%, an acid number of 8.9 mg KOH / g, a (theoretical) number of OH of 101 mg KOH / g and a viscosity of 50 dPas (original). The average molecular weight, by number, Mn, is 1350, the average molecular weight, by weight, Mw, is 7830, and the polydispersity Mw / Mn is 5.8 (each determined by gel infiltration chromatography against a standard of polystyrene ).

III.3 Preparation of a polyester resin A3: 796 parts of trimethylolpropane, 540 parts of isononanoic acid, 821 parts of phthalic anhydride and 83 parts of xylene were placed in a 4 liter condensation polymerization vessel equipped with stirrer, steam heated column and water separator, and They warmed up slowly. The condensation was carried out at a temperature of a maximum of 190BC, up to an acid number of 15 mg KOH / g and a viscosity of 5.3 dPas (60% in xylene). The batch was then cooled, diluted to 130 ° C with 910 parts of Shellsol A, and further cooled to room temperature.

The resulting polyester has a solids content of 66.5%, an acid number of 13 mg KOH / g, a (theoretical) number of OH of 104 mg KOH / g and a viscosity of 22 dPas (original). The average molecular weight, by number, Mn, is 1241, the average molecular weight, by weight, Mw, is 5843, and the polydispersity Mw / Mn is 4.71 (each determined by gel infiltration chromatography against a standard of polystyrene ).

III. . Preparation of a polyester resin A4; 848 parts of trimethylolpropane, 444 parts of isononanoic acid, 876 parts of phthalic anhydride and 83 parts of xylene were placed in a 4 liter condensation polymerization vessel equipped with stirrer, steam heated column and water separator, and They warmed up slowly. The condensation was carried out at a temperature of a maximum of 190 ° C, up to an acid number of 18 mg KOH / g and a viscosity of 80 dPas (60% in xylene). The batch was then cooled, diluted to 130 ° C with 1200 parts of Shellsol A, and further cooled to room temperature.

The resulting polyester has a solids content of 66.5%, an acid number of 16 mg of KOH / g, a theoretical number of OH of 114 mg of KOH / g and a viscosity of > 90 dPas (original). Due to the high viscosity of the resulting polyester, no further reactions were performed.

IV.1. Preparation of acrylate resins El a E5 and Cl a C6, containing hydroxyl groups The preparation of the acrylate copolymers was, in each case, carried out in a polymerization vessel, 4 liters, of stainless steel, equipped with a stirrer, reflux condensing, an addition of monomer and an addition of initiator. The components, specified in each case, were weighed and added in Table 1, and then the initial charge was heated to 165BC.

All additions were started at the same time; the addition of monomer was introduced at a uniform rate over the course of 4 hours, and the addition of initiator was introduced at a uniform rate over the course of 5 hours. During the polymerization, the temperature in the vessel was maintained at 160-165BC.

After this, the polymerization was continued for an additional 2 hours. The resulting acrylate resin solution had a solids content of 80%. The temperature was then lowered to 120 ° C and the acrylate resin was diluted with butyl acetate to a solids content of 65%, and the amount of benzoic acid indicated in Table 1, or the amount of t-butylbenzoic acid or hydroxystearic acid indicated in Table 1.

The polyester resin Al or A2 or A3 and the commercially available vinyl ester Versatic acid (VeoVa 10 commercial product from Shell Chemie) were weighed in each case, in the amounts specified in Table 1, and added to the initial charge.

The amounts of styrene, OH monomer and methyl methacrylate indicated in each case were weighted in Table 1, and added in the monomer addition. 14 parts of di-tert-butyl peroxide, 44 parts of Shellshol A (aromatic solvent mixture, which can be obtained commercially, having a boiling range of 165 to 185 * 0) and parts of xylene Weighed and added to the addition of initiator. This composition of the initiator addition is used in the preparation of all acrylate resins.

IV.2. Preparation of E6 acrylate resin, containing hydroxyl groups The preparation of the acrylate copolymer according to the invention was carried out in each case in a 4 liter stainless steel polymerization vessel equipped with stirrer, reflux condenser, addition of monomer and addition of initiator. The components, indicated in Table 1, of the initial charge, the addition of monomer and the addition of initiator were weighed and added, and then the initial charge was heated to 165 ° C.

All additions were started at the same time; the addition of monomer was introduced over the course of 4 hours, and the addition of initiator was introduced uniformly over the course of 5 hours. During the polymerization, the temperature in the vessel was maintained at 160-165 BC. After this, the polymerization was continued for an additional 2 hours. The resulting acrylate resin solution had a solids content of 80%. 7.5 parts of phthalic anhydride were added at 165 aC, and the temperature was maintained at 165 BC for approximately 2 additional hours. The temperature was then lowered to 120BC and the acrylate resin was diluted with butyl acetate to a solids content of 65%.

The polyacrylate resin obtained in this way has a solids content of 64.4%, an acid number of 4.4 mg KOH / g, a viscosity of 3.0 dPas (55% in butyl acetate) and an hydroxyl number of approximately 90 .

IV.3. Preparation of C7 acrylate resin, containing hydroxyl groups The preparation of the C7 acrylate resin, which contains hydroxyl groups, was carried out analogously with the preparation of the E6 acrylate resin, but adding 7.8 parts of hexahydrophthalic anhydride instead of phthalic anhydride.

IV. . Preparation of C8 acrylate resin, containing hydroxyl groups The preparation of the C8 acrylate resin, which contains hydroxyl groups, was carried out analogously with the preparation of the ac acrylate resin, the acrylic acid was likewise weighed and placed in the monomer addition and added with the other monomers.

IV.5. Preparation of C9 acrylate resin, containing hydroxyl groups 177 parts of Shellsol A and 113 parts of VeoVa 10 were weighed and placed in the initial load. 565 parts of styrene 250 parts of hydroxy-n-butyl acrylate 201 parts of methyl methacrylate 22. 6 parts of di-tert-butyl peroxide, 71 parts of Shellsol A (aromatic solvent mixture, commercially obtainable, having a boiling range of 165 to 185 aC) and 40 parts of xylene Weighed and placed in the addition of initiator.

The polymerization was performed analogously with the preparation of the polyacrylate Cl resin, heating the initial charge to 165 aC. All additions were started at the same time; the addition of monomer was uniformly introduced over the course of 4 hours, and the addition of initiator was introduced uniformly over the course of 5 hours. During the polymerization, the temperature in the vessel was maintained at 160-165 ° C. After this, the polymerization was continued for an additional 2 hours. The resulting acrylate resin solution had a solids content of 80%. The temperature was then lowered to 120 aC and the acrylate resin was diluted with butyl acetate to a solids content of 65%. Then 3.94 parts of benzoic acid were added. After this, 1133 parts of polyester resin Al were added to the polyacrylate resin solution.

The polyacrylate / polyester resin mixture obtained in this way has a solids content of 64.5%, an acid number of 4.0 mg KOH / g, a viscosity of 7.2 dPas (55% in butyl acetate) and a number of hydrochloride of about 90. Due to the high viscosity of the polyacrylate / polyester resin mixture, no coating composition was prepared using this mixture.

V. Preparation of the coating compositions El a E6 and Cl a C8 (Comparative Examples) V.l. Preparation of the curing agent solution The curing agent solutions are prepared by mixing the components specified below: 4 parts of catalyst solution 1 '50.6 parts of Desmodur N 33902) 10.0 parts of solvent naphtha 7.5 parts of xylene 1.5 parts of n-butyl acetate 98/100 0.6 parts of coating additive Baysilon OL4431 14.0 parts of 2-acetate of 1- methoxypropyl 11.0 parts of butyl glycol acetate X) the catalyst solution described in section III.3. 21 polyisocyanate obtainable commercially from Bayer AG, a solution with a concentration of 90% in butyl acetate / solvent naphtha, 1: 1, of a trimer based on hexamethylene diisocyanate and with an average molecular weight, by number, of about 700, an average functionality between 3 and 4, and a content of uretdione groups of not more than 5%; 3) leveling agent, which can be obtained commercially, based on a polyether-modified methylpolysiloxane from Bayer AG.

V.2. Preparation of an adjustment additive An adjustment additive is prepared by mixing the components specified below: Xylene 15.0 parts Solvent naphtha 13.0 parts Petroleum alcohol 135/180 10.0 parts Butyl glycol acetate 3.0 parts n-Butyl acetate 98/100 50 parts 0 2-Acetate 1-methoxypropyl 5.0 parts Butoxyl 2.0 parts Dipentens 2.0 parts V.3. Preparation of a catalyst solution 1.0 parts of dibutyltin dilaurate were mixed with 50 parts of 98/100 butyl acetate and 49 parts of xylene.

V.4. Preparation of final layers El a E6 and Cl a C8 Final layers were prepared, adding 5.5 parts of an organic red pigment (commercial product Novopermort F2RK 70 from Hoechst), which can be obtained commercially, to 38.8 parts of the respective solution of acrylate resin, together with 3.2 parts of butyl acetate 98 / 100 The batch was first placed in a solvent at 2000 revolutions / minute for 10 minutes and then, with cooling, milled to a Hegmann particle fineness of < 10m Then, a mixture of 3.4 parts of 98/100 butyl acetate, 20 parts of a commercially available acrylate resin, containing hydroxyl groups, and having an OH number of 150 mg KOH / g was added. (commercial product Macrynal SM 510 N from Hoechst AG), 0.5 parts of a light stabilizer, which can be obtained commercially, based on a sterically clogged amine (commercial product Tinuvin 292 from Ciba Geigy), 0.2 parts of the catalyst solution described above and 28.4 parts of the respective acrylate resin solution, and the mixture was homogenized using an agitator (1000 revolutions / minute).

In order to prepare the final layers, in each case, 4 parts by volume of the resulting mixture were mixed with 1 part, by volume, of the curing agent solution described above, and 1 part by volume of the described adjusting additive. above.

V.5. Application of the final layers Then, the resulting final layer was applied to phosphatized steel panels that had been treated with filler. For this purpose, the phosphatized steel panels had been coated with a conventional filler, which can be obtained commercially (Glasurit Grundfüller commercial product [surface-priming layer] 283-1874 from Glasurit G gH, Münster) based on epoxide groups which contain binder and in an amino-functional curing agent, and are subjected to intermediate drying at room temperature for 1 hour. Then, the final layer is applied in 2 passes of dew, with an evaporation period of 15 minutes in between, and drying at 20BC for 16 hours. The thickness of the dry film is 50 to 60 m.

The panels coated in this way were then subjected to various tests. The results of the tests are shown in Table 3. or Explanations of Table 1 Al, A2, A3 - polyester resin Al, A2 and A3, respectively VeoVa = mixture, commercially obtainable, of vinyl esters of saturated aliphatic monocarboxylic acids having predominantly 10 carbon atoms and branching at the carbon atom.

HBA = 4-hydroxy-n-butyl methacrylate HEMA = hydroxyethyl methacrylate HPMA = hydroxypropyl methacrylate HEA = hydroxyethyl acrylate MMA = methyl methacrylate AA - acrylic acid BA = benzoic acid PA = phthalic anhydride HSA = hydroxystearic acid HPA = hexahydro-stearic anhydride tBBA = t-butylbenzoic acid Table 2: Characteristics of acrylate resins and acrylate / polyester resin mixture Table 3: Test results of the coatings resulting from Examples 1 to 6 and Comparative Examples Cl to C8 Example Assimilation Leveling Resistance Duration Test Tesa Regu-Pak test of fog to resistance, spray resistance solvent container to removal Removal by tape Adhesive tape 1 2 3 1 4-5h 1-2 1-2 Cl 2 4 2 5h 2 2 1 C2 2 2 5 6h 4-5 4-5 C3 2 2 5 6-7h 5 5 2 2 2 2 6-7h 3 3 C4 2 2-3 4 6-7h 4 4 C5 2 2 4 7h 4 4 3 2 3 -1 3-4h 2 2 4 2 3 1 5h 2-3 2-3 5 2 2-3 1 4-5h 1-2 1-2 6 2 2-3 1 '4-5h 3 3 C6 2 4 1 3 -4h 3 3 C7 2 2 1 5-6h 4 4 C8 2 4 2 4-5h 3-4 3-4 Summary of test results: The assimilation of dew mist is equally good in all examples. A classification of > 3 or more for leveling is no longer acceptable in practice, so that the coating compositions of the Comparative Examples Cl, C6 and C8 present unacceptable results.

The solvent resistance of the resulting coatings is only acceptable with a rating of 2 or better. Coatings that have a classification of > 2 have tarnish phenomena and are no longer acceptable. Therefore, the coatings of Comparative Examples C2, C3 and C5 are no longer appropriate with respect to solvent resistance. All coating compositions show a suitable package life of at least 3-4 hours.

In the most important criterion of the coatings, the test of resistance to removal by adhesive tape, the classification for acceptable coatings must be at least 2-3 or better. Therefore, the coatings of Comparative Examples C2, C3, C4, C5 and C8 exhibit a resistance to removal by adhesive tape which is completely inadequate. The coating of Example 1 presents the best resistance to removal by adhesive tape.

Claims (12)

The claims we claim are:

1. Coating compositions comprising: (A) at least one binder containing hydroxyl groups, (B) at least one crosslinking agent and (C) at least one aromatic mono and / or polycarboxylic acid and / or at least one anhydride of an aromatic mono and / or polycarboxylic acid.

2. Coating compositions, according to claim 1, characterized in that said component (A) comprises a polyester resin containing hydroxyl groups, an alkyl resin containing hydroxyl groups, a polyacrylate resin containing hydroxyl groups , a polyurethane resin containing hydroxyl groups, a polyether resin containing hydroxyl groups or a mixture of said resins containing hydroxyl groups.

3. Coating compositions, according to claim 1 or 2, characterized in that said component (A) comprises an alkyl or polyester resin containing hydroxyl groups.

4. Coating compositions, according to claim 3, characterized in that said component (A) comprises an alkyl or polyester resin containing hydroxyl groups, which can be obtained by reacting: pl) polycarboxylic acids or their esterifiable derivatives, together, if desired, with monocarboxylic acids, p2) polyole, together, if desired, with monools, and p3) if desired, other modifying components.

5. Coating compositions, according to claim 5, characterized in that the component (A) comprises a polyacrylate resin containing hydroxyl groups.

6. Coating compositions, according to claim 5, characterized in that said component (A) comprises a polyacrylate resin containing hydroxyl groups, which can be obtained by polymerizing: (a) from 5 to 50%, by weight, preferably from 10 to 35%, by weight, of one or more monomers selected from the group consisting of 4-hydroxy-n-butyl acrylate, 4-hydroxymethyl methacrylate -butyl, 3-hydroxy-n-butyl acrylate, 3-hydroxy-n-butyl methacrylate and / or hydroxyethyl methacrylate, (b) from 0 to 50%, by weight, preferably from 0 to 30%, by weight, of a monomer copolymerizable with unsaturated ethylene, which is different from (a) and contains hydroxyl groups, or a mixture of said monomers , (c) from 5 to 95%, by weight, preferably from 15 to 55%, by weight, of an aliphatic and / or cycloaliphatic ester of methacrylic and / or acrylic acid which is different from (a) and (b), or a mixture of said monomers, (d) from 0 to 30%, by weight, preferably from 5 to 15%, by weight, of a copolymerizable vinyl ester which is different from (a), (b), and (c) or a mixture of said monomers, (e) from 0 to 85%, by weight, preferably from 15 to 60%, by weight, of an aromatic vinyl hydrocarbon that is different from (a), (b) i () and (d), or a mixture of said monomers, and (f) from 0 to 10%, by weight, preferably from 0 to 8%, by weight, of an additional monomer with unsaturated ethylene, which is different from (a), (b), (c), (d) and (e), or a mixture of said monomers, the sum of the proportions, by weight, of the monomers (a) to (f) in each case will be 100%, by weight.

7. Coating compositions, according to claim 2, characterized in that said component (A) comprises: (Al) from 20 to 60%, by weight of at least one alkyd or polyester resin containing hydroxyl groups Y (A2) from 40 to 80%, by weight, of at least one polyacrylate resin that has been prepared, at least partially, in the presence of the component (Al).

8. Coating compositions according to one of claims 1 to 7, characterized in that they contain as component (B) at least one di and / or polyisocyanate.

9. Coating compositions, according to one of claims 1 to 8, characterized in that the amount of component (C) is 0.1 to 2%, by weight, based on the weight of the component (A).

10. Coating compositions according to one of claims 1 to 9, characterized in that they contain as component (C), phthalic anhydride, phthalic anhydride with alkyl and / or alkoxy substitution, a half ester of phthalic anhydride, a half ester of phthalic anhydride, phthalic anhydride with alkyl and / or alkoxy substitution, benzoic acid or benzoic acid with alkyl and / or alkoxy substitution.

11. A process for the production of a protective and / or decorative layer on a substrate surface, characterized in that a coating composition according to one of claims 1 to 10 is applied.

12. A process, according to claim 11, characterized in that the protective and / or decorative layer is a finishing coating.